The continuing proliferation of electronic equipment of all sorts has prompted governments and their various regulatory agencies to promulgate ever stricter limits on the amount of electromagnetic interference (EMI) that devices may generate. As these stricter rules take effect, and as computer equipment gets faster and faster, even simple cabling solutions that were satisfactory five or ten years ago are not suitable today.
Consider, merely as an example, a shielded SCSI or HIPPI connector on a PCI/ISA I/O card. A number of RF connections must be made to satisfactorily ground the shield in the connector and the shield in the cable. Typically, these include: a connection from the cable shield to the shield of the backshell of the cable connector; cable connector backshell shield to the rim of the cable connector; cable connector rim to card connector rim; card connector rim to card bulkhead plate; and, card bulkhead plate to the system enclosure (chassis). If any one of these connections is a poor RF connection the shielding of the connectors and the cable are compromised, and the equipment may fail to meet the standards it was certified to meet. This is especially true of I/O cables, since they are apt to be applied to and removed from their mating connectors many times during the life of the equipment. It would be desirable if there were a way to ensure good shielding performance despite deterioration in the ground path connections not within the cable connector itself (i.e., in the cable connector to card connector interface and on into those involving the card and chassis).